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                                  What Are Drug Screen Cut-Off Levels?

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Understanding AS/NZS 2019 Standards for Urine & Saliva Drug Testing

If you’re researching workplace drug testing in Australia, you’ll come across the term “cut-off levels” — but what exactly are they, and why do they matter? In this article we break down what cut-off levels mean in practical terms, how they’re set under Australian and New Zealand Standards, and the differences between urine and saliva testing.

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What Are Cut-Off Levels?

A cut-off level is a predefined concentration of a drug (or its metabolite) in a biological sample — such as urine or saliva — above which a test result is considered non-negative or positive for that substance. If the drug concentration in a sample is below the cut-off level, the test returns a negative result.

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These thresholds are fundamental to drug screening. They help ensure:

  • Consistency across all tests and laboratories

  • Reliability in detecting impairment or drug use

  • Fairness, by reducing false positives due to low-level exposure

  • Compliance with legal and workplace safety requirements

 

Saliva Drug Testing – AS/NZS 4760:2019

For oral fluid (saliva) testing, the current Australian/New Zealand Standard is AS/NZS 4760:2019: Procedure for specimen collection and the detection and quantification of drugs in oral fluid. This Standard sets the cut-off levels that saliva drug test kits should use when screening for specific drug classes.

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Screening Cut-Off Levels (On-Site)

The following are the commonly accepted saliva cut-off levels used in workplace drug screening:

Amphetamine-type substances50 ng/mL

Cannabinoids (THC)15 ng/mL

Cocaine & metabolites50 ng/mL

Opiates50 ng/mL

Oxycodone40 ng/mL

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Why oral fluid? Saliva testing is a less invasive way to detect recent drug use. It generally reflects very recent use — typically in the past few hours to days, depending on the drug — making it suitable for pre-employment, random or incident-related screening.

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Urine Drug Testing – AS/NZS 4308

For urine testing, the main Standard used by Australian drug screening programs is AS/NZS 4308 (Procedure for specimen collection and the detection and quantitation of drugs of abuse in urine). While previously updated in 2008 and revised in 2023, the urinary cut-off levels remain widely recognised and applied across workplace testing programs.

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Screening Cut-Off Levels – Urine

Amphetamine-type substances300 µg/L

Benzodiazepines200 µg/L

Cannabis metabolites50 µg/L

Cocaine metabolites150 µg/L 

Opiates300 µg/L

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Urine testing covers a longer detection window than saliva and is one of the most common forms of workplace screening, especially for pre-employment and routine compliance testing.

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In Summary

  • Cut-off levels define the minimum drug concentration that will trigger a non-negative result.

  • Australian drug testing standards specify these levels for both urine (AS/NZS 4308) and saliva (AS/NZS 4760:2019) testing.

  • Saliva tests use ng/mL levels, while urine tests use µg/L levels.

  • Understanding these thresholds is essential for reliable, fair and compliant drug testing programs.

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